I've found that this item really buffs Renekton's midgame. it makes his W into a lifestealing AoE nuke as well as a notional stun, gives him an extra 1.0 AD scaling AoE nuke, and refulls his hp if he gets ignored.

It's strong on champions that either

a) lack sustain need an extra ad-scaling spell to burst people harder (Riven, Zed, Pantheon)
b) have the elusive combination of ad-steroid, lifesteal steroid, attack speed steroid, and enough durability to sit in the middle of the enemy team and use all those steroids (Nocturne has two steroids and a spell shield that gives even more AS, Lee Sin has AS and lifesteal and a shield/armor buff, Olaf has all of those, Mundo has the AD steroid and a ton of survivability, AD Sion has all of those, Nasus has AD, lifesteal and durability)

The active and the passive seem to not work together well. It seems like an item for melee ad carries to clear jungle with, but melee ad carries aren't viable in general and the item is too expensive for just jungle clearing.

The AOE really isn't that significant against champion. Just makes pushing a bit easier.

Any resonable comparisons between this and bloodthirster?

this is the worst new item in the game, its costs are outragerous and you get basically nothing

I like it on WW but that is just me, this and Blade of the Ruined King I have been experimenting with together. I have found it to work nicely but they are very costly.